Superheater pipe connection and method of making the same



Jam, 18, @230 7 1,442,458

D. H. WILSON ET AL SuPERHEATR PIPE CONNECTION AND METHOD OF MAKING THESAME. FILED 001'. 2 I 920.

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A TTORIVEYS 2 IN IVTURS M4 Patented Jan. 1%, i923 DAVID H. "WILSON, OFEVOBTEHDEZ'KE, NEW JERSEY, AND JAMES E. FULLER, OF FEEIDONIA, NEW] 103K; PATTII INE NELSON ADllilIlTISTIELATBIX OF SAID DAVID H. WILSON,DECEASED.

SUPERHEATEB Z IPE GQNNEGTIQN AND TEETHGTD 0F I'IIAKING THE SAME.

Application filed Gctober- 2, 1920. Serial No. 414,311.

To all whom '52, may concern Be it known that we, DAVID lVILSON, acitizen of the United States, and a resident of Wortendyke, county ofBergen, and State of New Jersey, and JADIES .l l. FULLER, a citizen ofthe United States, and a resident of Fredonia, county of Chautauqua,State of New York, have invented certain new and useful Improvements inSunerheater Pipe Connections and Methods of Making the Same, of whichthe following is a sgeci fication.

Our invention. relates to a method of forming; nipples upon the ends ofmetal tubes and. is particularly applicable to the tubes of supcrheatersfor steam. boilers. Our invention is herein disclosed as applied to thattype of superheaters in which the tubes are connected to suitableheaders. Que object of our invention is to provide improved nipple whichwill form a tight joint at the header and which will be cheap, durable,easily asembled, with a homogeneous crystalline structure free fromcracks and capable of withstanding high temperatures without burningout. Other objects and advantages will hereinafter appear.

In the accompanying description, we have disclosed one method ofcarrying; out our invention, reference being had to the accom panyingdrawing in which:

Figure 2. represents a section of a superheater pipe stock upon the endof which a sleeve of additional metal stock has been fitted.

Figure 2 represents the pipe stock and sleeve shown in Figure 1 afterthe first heating and forgingoperation has taken place showing themanner in which the shoulder is molded.

Figure 3 shows the same pipe stool: and sleeve in its final conditionafter the second heating and forging operation, showing the shoulderfurther upset and the bead which has been formed upon the end of thetube.

Figure 4 shows one of the superheater tubes in operative position withits end clamped into the orifice of the header.

In the manufacture and use of superheaters for steam boilers,considerable trouble has been experienced in fitting the ends ofsuperheater' tubes into the superheater headers. It has been founddifficult to make a tight joint capable of withstanding the intense heatto which the parts were subjected without burning" out. In order toavoid this difticulty, superheaters have been made in which the ends ofthe tube stock have been thickened by crimping and mold .ing into theform of a hollow ball joint, which were then clamped tightly to theheader orifices. According; to this crimpingmethod, an armular groove orcrimp was first formed in the tube stock near the end. The metal in thiscrimped portion was then squeezed together and folded back to form anannu lar clamping;- shoulder. The end of the tube was also expanded andfolded back into a bead. The above operations were carried out in asuitable upsetting machine in which the heated metal was subjected topressure between plungers and dies. The superheater tubes formed by theabove method were found to be weak, owing to the existence of permanentcracks and laminations sometimes c l in the metal of the tube Jedcold-shui' s which were necessarily formed during; the above mentionedcrimping and folding operations.

7' practice many failures occurred in the thickened bead and shoulderportions of these tubes and upon examination, it w s found that themetal of the tube was fatiuu and had a dangerous crystalline structure csed by the e) ssive deformation to which the metal. gathered up fromtoclt in the tube was subjected. Morethe microscopic structure of themetal found to be heterogeneous and the metal s also brittle causingfrequent accidents iralrino; constant shut dcwns for renewals necessarv.The formation of coldshuts particularly frequent when the diameter ofthe tube was either smaller or larger than standard, in which case largecracks visible without a microscope were often formed at the shoulder orhead.

Another disadvantage in the above method is that an excessive number ofdistinct operations and heats were required which were very detrimentalto the metal structure.

According to the method which we have discovered, the end of asuperheater tube may be fashioned in only two operations and the abovedisadvantages can be entirely avoided. Moreover by our method thestrength of the ball joints or nipples will be greater than the strengthof the tube stock itself.

In carrying out our improved method the first step consists in fittingsleeve 1 of additional metal stock upon the end of a tube 2, as clearlyindicated in Figure 1. The end of the tube 2 with its sleeve is thenheated to a forging temperature and placed in the die of any suitabletype of upsetting machine, similar to that employed in the methodpreviously described. A suitable plunger or mandrel is then forced intothe interior of the tube and pressure applied, causing the added stockof the sleeve to become welded to the pipe stock and up setting ashoulder 13 at the rear of said sleeve without in any way crimping ordistorting the original tube stock itself, the metal for the shoulderbeing entirely gathered from saidsleeve.

The next operation consists in re-heating the end of the tube to aforging temperature and again placing it into the upsetting machine. Asecond plur 'er or mandrel of slightly diilerent form then forced insideof the tube and pressure applied upsetting the iEOIWLUTl port-i n of thethe form of a head 4.- cl approznmately the proper. size to fit thebeveled socket 5 of the superheater header 6, the latter being shown inFigure 4C. In this operation some of the metal of the end of the pipewill be turned or drawn outwardly so as to term a part of the outer faceof the ball or niple. l

The beaded tip l of the nippleinay then be ground to accurately it thebevelled socket 5 of the header conduit and the rear of the shoulder 3may be machined in a lathe so that it will [it the collar *4" ot the jawS of an adjustable clamp. The other jaw of the clamp (not shown) bearsupon the opposite side oi the header.

lVhile'we have given an illustration oi the application of our inventionto the manufacture of superheatcr tubes it is obvious that the inventionmay be employed equally eeve into tube.

formed upon the outside of said tube from an additional supply of metalstock.

2 A method of forming a nipple upon the end of a metal tube whichcomprises providing said tube with a concentric sleeve of additionalmetal stock, applying heat and pressure to said tube and sleeve to forcea part of the sleeve into an annular shoulder, and applying heat andpressure to the outer end oisaid tube and sleeve to force the outer 4:.A method of forming a ball joint or nipple upon the end of a metal tube,to enable said tube to be clamped into a socket opening in a conduit,which comprises providing said tube with a concentric sleeve oiadditional metal stock, forming a shoulder on said tube from the: metalof said sleeve in one forging operation and a bead or ball at the end ofthe tube in a second operation and machining the'ball to lit the socketopening. j

5. A method for forming a ball point or nipple upon the end of atube toenable said tube to be clamped lllilOuZL socket openin a, conduit, whichcomprises providing tube with a concentric sleeve of additional tubestock, upsetting said sleeve stool: to form a shoulder and an end beadand welding said sleeve, tube, bead and shoulder into a homogeneous masstree from cracks, said nipple having a strength at least equal to thatof the cylindrical portion of the 6. A method oil produchig a nipple orball joint upon the end oi a metal tube which consists in providing saidtube with a sleeve of additional metal stool: and applying heat andpressure to force a part of the metal of said sleeve into the form of anipple and to molecularly unite said sleeve and tube.

7. A method of producing a nipple or ball joint upon the end oi? ainetal tube which consists in providing said tube with a sleeve ofadditional metal stock and applying pressure to force a part of themetalot said sleeve into the form of a nipple.

In testimony whereof, we have ailixed our signatures to thisspecification.

DAVID I'L'VV'ILSON. JAMES E. FULLER,

